This Week in Wood » Guitar Making

Sanding a guitar body

glennth — Thu, 05 Jan 2012 23:59:20 +0000

After a bit of time re-establishing the routine with getting kids to school and doing homework with the kids, I got back in the shop. I had left off finishing the install of the binding and purfling on guitar 3′s body. I had done a little clean up and wanted to finish that up.

I use way too much glue. I must be addicted to it because I can’t help myself applying as much as I do even though I know that the squeeze out will be wasteful and messy. The mess makes it really hard to clean up. Sanding it uses a lot of sand paper because the glue dries hard. Scraping is hard on the scrapers and some times, I get extra tear out when a glue bit sticks too hard to the wood. I really need to work on this but for this guitar body, it was too late.

Clean up is a mixture of sanding and scraping. I’m still new to scraping so I tend to over use the sand paper. With bending and purfling, it’s important to keep the sides square and not round over the binding (still perfecting my own technique on this but each guitar gets better). The goal is to have an even thickness of binding around the guitar body and have no round over though we will ease the edges before it’s time to finish (cause, trust me you do not want to play a guitar that the body doesn’t have it’s edges eased – they are sharp).

After the clean up, I do a quick sanding going from 80 grit all the way to 220 grit. I will probably touch up the body again with 220 before I apply the finish.

Above you can see the current state of the guitar bodies. Back left is guitar body 2 which has binding and purfling installed. Back right is guitar body 3 which also has the binding and purfling installed. In front is guitar body 4 which I will begin the binding and purfling installation next time.

This is guitar body 2 with it’s binding and purfling.

This is guitar body 3 with it’s binding and purfling.

Next step will be to pre-bend the binding for guitar body 4 and then on to glue up, clean up and sanding. After that, it’ll be time for the necks.

Post from: This Week in Wood (c)2009 Glenn Thompson. For Downloads, Pictures, and other great content go to This Week in Wood. See This Week in Wood Legal Information Page for specific usage rights.

Sanding a guitar body

Guitar 3 has been bound!

glennth — Fri, 23 Dec 2011 23:56:41 +0000

Today, I’ll show you a little about how I improved my binding and purfling install.

Below you can see that the first half is finished. Before finishing the 2nd half, you need to square up the ends so that you can get a flush joint. In my case, I usually overextend the glue joint for the first half and have to scrape and chisel out material to get it to be a proper fit. I do my best to line the joint up with the center line of the sound board.

Below you can see that I pre-tape the binding and purfling with a strong focus on the proper order of the pieces, matching the first half so that you get a good look.

It’s important to have all the supplies ready for the glue up. In this case, it means lots of pre-cut tape ready to clamp down the glued up purling and binding. I use an acid brush to apply the glue and dixie cups are always my friend.

I can only show the beginning because after that it’s all about moving along and not letting the glue to set up prematurely. I usually apply enough glue for about 6 inches or so. I apply the glue to the guitar body where I’ve routed the groove and to the purfling pieces and binding. I know that I apply too much but my theory is to allow some to seep into the gaps where possible. It’s really important to push the binding tight which in turn pushes the purfling tight before snugging up the glue.

Carefully work around the body and then get the rubber out and start wrapping and stretching it around the guitar body. The stretch is what gives the extra clamping pressure so make sure you get an ample stretch.

Tomorrow I will get to see how it looks. I will sand the top and back but focus on scraping with the sides due the curves. The back seemed nice and tight so I’m hopeful that we’ll get a good looking application.

It’s a good day!

glennth — Thu, 22 Dec 2011 23:03:18 +0000

Today was a good day!

I decided to try a new approach to the initial glue up.

In the previous glue ups, I run into a problem that the purfling is not pre-bended (it’s just too thin to even try) while the binding is pre-bended. This aggravates the nature of thin pieces of wood getting tangled.

Today, I temporarily taped the purfling down so that it acted closer to being pre-bended. This reduced the tangling effect by at least one order of magnitude and maybe more.

Only one issue is that I got the order wrong in glue up but was already half way through when I figured this out. Fortunately, I can ensure that the other half of the top is the same so it really won’t be a problem and I will probably be the only one who cares or notices. I wanted the pattern for the purfling to be dark wood, blood wood, ebony, then the binding but instead wound up being ebony, blood wood, dark wood and then the binding.

At the bottom of the picture, you can just make out the colors of each piece of purfling. The dark wood is close in color to the ebony so again, it’s probably only me that will notice or care.

I also felt that the tightness of the glue up was great so later this afternoon, when I remove the rubber and tape, I’ll find out.

Less Swearing…

glennth — Thu, 22 Dec 2011 00:40:34 +0000

I got back to my shop yesterday and returned to working on building 3 guitars. The step I’m on (installing purfling and binding) is not fun and actually quite frustrating. Yesterday, I was swearing a lot. In fact my wife, Kathy, came out to check on me.

I’ve broken the job down into 4 installs per guitar. Yesterday was the first for the last 2 guitars and today, I did another. I’m proud to say that no swearing or yelling happened during the install. I’m not saying it went perfectly but instead I remained focus not he task.

The issue, as I mentioned in yesterday’s post, is keeping the 4 pieces of wood in the proper orientation and order. The second issue is ensuring that the install is completely clamped to the guitar body. The first issue can only be solved by more hands and if that’s not possible, slow methodical work. The second issue is something I attack with 2 strategies. The first one is using my hands to clamp and then blue tape to hold it down and work around. The second is to add the rubber and stretch it around the body providing additional pressure on all the key points ( the main one seems to be the waist).

Tomorrow I will continue and by Saturday, this body should be to the point where I start scraping and sanding the binding and purfling to make it look good.

Back To Work

glennth — Wed, 21 Dec 2011 00:03:35 +0000

A few hours ago I got back to my shop.

As many of you might know, my current project (or projects) involve building 3 guitars from scratch. To date, I’ve built 3 bodies which include 2 with cutaways and 1 with full body. I’ve roughed 3 necks out including the headstock.

Right now, I’m working on the purfling (a purely decorative element that works with…) and the binding (provides a hardwood edge to the sound board containing and focusing the sound). I’ve finished 1 body and today began the 2nd body.

The task is very frustrating and is kind of like brading hair but instead of twisting it in an organized fashion, I’m taking 2 very small skinny threads of wood and a slightly larger one and trying to keep them in the proper order while glueing and clamping in place as I work around the body. It’s not as easy or simple as I make it out to be either.

I glued up 1/4th of the 2nd guitar. We’ll see how it turned out after I get the tape and rubber clamps off.

I’ve decided to just get this job done and try to learn from each attempt. I want to get these guitars done so I can move on to the next project (either a desk or a work bench, I’m still pondering).

Purfling…what a funny word!

glennth — Fri, 14 Oct 2011 18:45:45 +0000

Purfling is a word that defines material between the binding and the top or back wood on a string instrument. Binding is a word that defines the outer most material surround the top and back wood on a string instrument. The purfling is decorative but the binding actually provides some function. First the binding provides protection for the end grain of the top and back woods and second (though I’ve not seem any testing that verifies this but it sounds right) the binding provides a hard border for the top wood (also called the sound board) for a string instrument which affects the tone waves.

On my 3rd guitar body (a full body, no cutaway), I decided to start with the purfling channel.

In a test board, I cut several channels adjusting the router bit’s depth of cut until the purfling was protruding just a smidge (and yes, it’s a technical term though I’ve also heard skosh). I then pick out a bearing which will provide the channel width to hold the purfling and the binding. In the picture above you can see that for the purfling, I have 3 layers (ebony, bloodwood, and a dark brown wood) The binding is a piece of maple bent to the shape of the guitar with a matching dark brown wood edge for the bottom of the binding. The purfling is so thin that it doesn’t need to be pre-bent.

I then use the tested set up to rout the purfling channel into the back and top of the guitar body. Remember in a previous post, I talked about the channel not being square (this is due to the router riding along the top and back and the top and back are arched ever so slightly). I use an adjustable square to test the squareness of the channel and a small chisel as a scraper to adjust the squareness of that channel.

After a lot of scraping, I finally get the fit to be perfect. After I finish both sides of this guitar body, I’ll work on the 4th guitar body (which is a cutaway model) then it will be time to repeat for the binding channel.

Guitar Building – Back at it!

glennth — Tue, 11 Oct 2011 20:02:22 +0000

It’s been a while since I worked on my guitars. Now it’s time to get back to it (not that I’ve exhausted all my distractions but really…I need to finish these babies!).

On the right you see my second guitar body. I had already finished the purfling and binding though I don’t consider it a stellar job. I certainly learned a lot from the process. I learned a bit about repairing them though I still have a bunch more learning to get the repairs to look seamless. Of course, i’d rather not need the repairs so I need to learn more about getting the install process to be more flawless. I think the biggest issue was that I did not have the grooves for the purfling and binding parallel to the sides. I used a router and it was a bit angled. I think that I will keep with that method but then focus on more hand tool work to get those grooves parallel to the sides.

On the left, you see my third guitar body. I’ve got the bindings pre-bent (the second guitar body I bought pre-bent bindings). and they turned out well. I will start the groove making and squaring process over the next few days (given my schedule, I’m hoping on Thursday).

I’m looking forward to tackling this luthier business again.

Bending Bindings

glennth — Thu, 04 Aug 2011 21:52:49 +0000

Today, I turned to Guitar #3. This guitar is a full body (no cutaway) OM sized guitar. My intention for this guitar is to give it to my youngest son, Mitchell. Mitchell is currently 10 and is learning piano. I have offered him the choice to change to guitar when he is 12 and he is very excited about it.

The body is put together and now it’s time to turn to the binding and purfling. For my previous guitar (#2, see previous posts) I used binding that I had pre-bent by LMI. I decided if I’m going to build more guitars that I would have to learn to bend wood so I got a thermostatic bender (tube) from LMI.

In the above picture you can see the bender in the front.

Bending was both easier and harder than I expected. It takes a slow and patient touch to avoid the nasty sound of cracking wood. For the binding, I did not moisten the wood. I’ve read conflicting opinions recently about whether or not moister is needed and decided to try the no moister route. The bending went find but I did notice that matching the exact shape of the guitar was more challenging.

To compensate for the difference in shape, I read a discussion that described closely bent would being taped to the body and then moistened and then the shape matches closer when the bindings dry.

Above you can see the results. I let you know the results next time.

Hobby vs Job

glennth — Mon, 01 Aug 2011 22:41:19 +0000

As a full time Dad, many might think that I have ample time for woodworking (my greatest passion outside of my wife and kids)…but they are just wrong. Yes, it would probably be possible to carve out time with some rules for the family – much like work at home parents… but that would be a job.

I don’t want my hobby to become a job though I see many woodworkers and luthiers discuss it. My original hobby was computers. Throughout high school and college I spent much of my free time programming (basic, pascal, C, assembly even). In high school I built a specialized accounting system for my parents business (a service/gas station) which they ran their business on till they closed it down. After college, I got a job at Toshiba and then eventually Microsoft and thought I was living the dream. At first, I was. I worked hard and had fun at my job. The problem is that with the overlap of a hobby and job, you rarely step away from either and so you never get any downtime. After about 10 years or so, I lost my luster for computers and tech and it just became a job. I was good at it and worked hard but when I was at home, I didn’t want to continue on. This probably was the seed for my next big hobby – woodworking.

Now I sometimes go into my shop for 15 minutes and then have to step away for my family. I might grump about it but I certainly do not begrudge this. The grump is just because being interrupted in any activity is no fun but ultimately, I’m a full time Dad to be with my family. Of course I do get other days where my family guards my time and I can get 8 solid hours in the shop if I want. Having family support is fantastic.

Over the last few weeks, I’ve been to my shop almost every day but mostly for a very short time. I’ve made some progress on the binding and purfling for my 2nd guitar body. I have mixed feelings about the results. Most of the results are great but there are sections that should be redone. I’ve decided to learn from this and move on to my 3rd guitar body.

I’m confidant that the sound from this body will be great. My goal for this guitar is to produce a great sounding work guitar for my brother. He lives in California and picks and pokes at guitar but has a great time doing it. I think he’ll appreciate a cutaway guitar.
The next guitar body is for my youngest son, Mitchell. He’s currently 10 but I have promised him at 12, he can switch from Piano to guitar. He’s very excited and will probably love the resulting guitar more than any person could. It’ll have been made by his Dad especially for him.
I think these goals are another example of the differences of hobbies vs jobs. With hobbies, you have the flexibility to be with your family but you also have the love to give to your family. Jobs can be about family but it is more indirect.

Mitchell as a Luthier

glennth — Sun, 17 Jul 2011 16:01:29 +0000

In my last post, I talked about my experience with Mitchell, 10 and Xander, 12 helping me install my bindings and purflings on the top of my second guitar build. I was very happy with both their help and focus. Anyone who has children knows that when you get your kids to help you, you are not always guaranteed that they actually help you.

Here you can see Mitchell showing off his work. He’s very proud and maybe that shows that we might have a future luthier among us.

Here I am showing the joint at the heel end of the top. I was super pleased with this. The joint is tight and nearly seemless.

Most of the binding on the top looks like this. We have a tight fit to the body at both the top and sides and each of the purfling pieces is tight against the other with no twisting.

This is the worst area. This happened on the side of the top with the cutout where I was nearly done. I had already had some breaks win the bloodwood (center piece that is red in color) purfling. This is where the cutaway straightens out and approaches the location where the neck will be joined to the body. You can see that the ebony (black and inside) purfling started to twist and separate from the body.

This is the location where I had the first break. This is on the second side (the first worked great) or the cutaway side. You can see here that the bloodwood purfling broke and I tried to fit another piece in. It was stressfull and I’m not sure I could have done it right anyways. Glue was already applied and the time was ticking so I could get the rubber rapping clamp around the body.

Both of these areas will need to be trimmed out and have a new patch put in. At this rate, I’m going to get better and better at patching the binding and purfling.

A True Luthier Experience

glennth — Wed, 13 Jul 2011 21:38:51 +0000

Today I wanted to tackle the other half of my 2nd Guitar build, specifically the binding and purfling. The first side/back side went fairly well and lessons were learned. I was very hopeful on tacking the second side/top side.

As I was going out to my shop, I asked my oldest (Xander, 12 years old) if he wanted to come and help me figuring an extra pair of hands couldn’t hurt. Of course, the ears on my youngest (Mitchell, 10 years old) perked up and he wanted to join us. Off we went into the vast unknown and predictions completely thrown out.

While I was prepping things for the install (getting tape pre-cut, glue pored and ready, brush for glue, cleared area for the glue up) I discussed how they could help. I assigned one of them to take pictures. Xander signed up for that. Here is his self portrait. You can see how focused he is on photo’s of the build and no goofing off. Please note that he took about 50 pictures and only about 15 were in focus enough to use.

Once jobs were assigned, we began. Through out the glue up pictures, you will see Mitchell who was my sus-luthier. I had Mitchell help with the glue and getting me tape and then finally attaching the rubber to clamp everything down.

During the process, we had a minor disaster happen. The purfling consists of 3 pieces and the middle piece decided to break when we had gotten to the second side. The boys were both incredibly helpful and I think we resolved it though we won’t know till the clamps and tape come off. I’m most worried about the large round at the bottom of the body on the cutaway side. I may have to do another patch it if doesn’t look good. Next came the clamping.

Because of the small disaster, it was a bit stressful but overall, I hope that I can convince them to help me more often when I’m in the shop. It was a good experience for them and I think they both had some fun while it was going on (except for the bit of cussing when the middle purfling broke off and bit more when it broke a second time).

Guitar 2 – More binding and purfling install

glennth — Mon, 11 Jul 2011 18:39:52 +0000

Now continuing the efforts to install the binding and purfling on the second guitar build, I found that using a rubber hose to add additional clamping pressure beyond the tape gives a better result especially at any tight curves like the waist or cutaway. In addition, I add clamps to those key areas. I may actually make some clamping blocks to give even better clamping pressure at those tight curves.

You can see that I really emphasize the rubber wrapping at the waist and cutaway.

I felt much better with this glue up. I used a brush to apply the glue and didn’t see or feel any twists in the purfling (won’t really know till clamping and tape is removed though).

Here is the finished (not before scraping and sanding) result:

No twisting and the tight corners were nice. Now it’s time to smooth the finish using scrapers and sandpaper.

I feel like I will be able to do the entire top side all at once next time.

Guitar 2 – Binding and Purfling repair

glennth — Fri, 08 Jul 2011 02:58:29 +0000

My first attempt at the binding and purfling went fairly well though I had some issues at the waist (the skinny part of the guitar body). The purfling twisted and the binding and purfling didn’t glue tightly against the body.

I had to carve out a small section and remove the bad piece around the waist. It turned out to be about 4″ or so. Used a knife, chisel and scraper to remove the binding and purfling. It came out easy and cleaned up easy.

I carefully cut pieces of binding and purfling to tightly fit the gap. I then installed it and used rubber tube to add additional clamping pressure and even added a clamp.

It turned out great. The purfling seemed right into the existing purfling. The binding had a great fit on one side but a small gap at the other. I may play at fixing that some more after all the binding/purfling is installed. I’m pleased with the repair though I really have to work at my smoothing techniques using scrapers and sand paper to get a really primo looking binding/purfling install.

And the results are…

glennth — Fri, 24 Jun 2011 22:34:57 +0000

And the results are…mixed.

Just a quick reminder, this is my first (Solo because I worked with 1 classmate and 1 teacher on my first guitar, which was a kit and used man made materials) attempt at installing binding and purfling. As I discussed in the previous post, the process went well…at least on the surface.

Let’s start with the positive results. If you break a guitar into halves and then note that there is a front and back, I have four areas/quadtrants to install binding and purfling in. This first attempt was on the back. Most of it came out very well.

The top picture shows that the 4 bands (3 purfling – dark wood, bloodwood, ebony; binding – maple) are tightly fit and give a really nice accent against the edge of the body and tie into the blood wood center strip on the back. The bottom picture shows the binding (which is actually maple with a very thin strip of dark wood on the bottom, pre-attached by my luthier wood supplier LMII) also has a very tight fit and blends really well with the side. I am super pleased with my choices and how these parts turned out.

Unfortunately, the waist of the guitar (the shape of a typical guitar is figure 8 like and the center where the pear gets thinner is the waist) didn’t turn out as well.

The top picture again shows the back but this time, you can see that there is a gap and maybe even a twist (I need to take a scaper to it to clean it up a bit). The bottom picture shows that the binding did not fit tightly against the sides.

I’ll spend some of the weekend researching strategies on how to repair this waist line and then come up with a strategy on getting the waist to fit tightly for my next attempt at a glue up.

Tomorrow, I’ll know…

glennth — Thu, 23 Jun 2011 22:03:20 +0000

Tomorrow, I’ll know how my initial try and binding and purfling turned out.

Using a trim router, did a lot of test channels. My trim router is a Festool MFK 700 and I chose a trim router instead of a full size because I felt it gave me more balance and control over the process. Using this router, I did feel quite good while doing the channels. The router bit that I used was from Luthier Mercantile International and was the Binding Cutter/Bearing Kit. The full kit comes with a router bit and 8 different size bearings which allow good adjustment for channel widths. Once I got something I was happy with, I cut the channel in one of the 3 guitar bodies I’m working on.

Sorry for the picture quality, I never got a macro capable camera and was clearly too close. The fit turned out nice. I’ve got 3 purfling pieces and the binding. The purfling consists of ebony, bloodwood, and a dark wood that matches the trim on the binding. The binding is maple with a dark wood trim on the bottom.

After the channels were cut, I breathed a little easier though one hard step was left and that was the glue up. I needed to apply glue to the channel and the pieces and work my way around taping the pieces down. The tape was my clamp. I used longer pieces of tape than we used in my class back last summer on my first guitar but I felt that this allowed for more clamping pressure. I applied glue about 5″ at a time which allowed me to control any twist in the purfling pieces. Twist seemed most difficult to control when just beginning though at the end, there was a lot of glue on my hand and on top of the purfling and binding that it was also hard to control.

It’s not a very exciting shot but it shows the tape clamping down the purfling and binding. Tomorrow is the day I’ll remove it and check out how it turned out. If it turned out fine, then I’ll be able to do the rest of the guitar in one sitting. I just didn’t want to do that in one sitting without a trial run. I’m hopeful!